Differential expression of transforming growth factor-beta receptors I and II and activation of Smad 3 in keloid fibroblasts

Dehydroepiandrosterone Suppresses Keloid Fibroblasts Fibrosis by Inhibiting the TGF-β1/Smad Signaling Pathway

The pathogenesis of keloid is complex and unclear, and current therapies of this condition remain unsatisfactory. Dehydroepiandrosterone (DHEA), a steroid prohormone, exhibits a wide range of pharmacologic activities, including anti-inflammatory and pro-immune effects, as well as anti-tumor and anti-fibrotic properties. Herein, the authors explored the potential effects and underlying mechanisms of DHEA on keloid fibroblasts in vitro. The authors' findings indicated that DHEA significantly inhibited the proliferation, migration, and invasion of keloid fibroblasts, while promoting cell apoptosis. In addition, DHEA significantly reduced the expression of fibrosis-related proteins in keloid fibroblasts by suppressing the TGF-β1/Smad signaling pathway. In conclusion, the authors' in vitro results highlight the therapeutic potential of DHEA as a promising candidate for keloid treatment.

Macrophage phenotype is determinant for fibrosis development in keloid disease

Keloid refers to a fibroproliferative disorder characterized by an accumulation of extracellular matrix (ECM) components at the dermis level, overgrowth beyond initial wound, and formation of tumor-like nodule areas. Treating keloid is still an unmet clinical need and the lack of an efficient therapy is clearly related to limited knowledge about keloid etiology, despite the growing interest of the scientific community in this pathology. In past decades, keloids were often studied in vitro through the sole prism of fibroblasts considered as the major effector of ECM deposition. Nevertheless, development of keloids results from cross-interactions of keloid fibroblasts (KFs) and their surrounding microenvironment, including immune cells such as macrophages. Our study aimed to evaluate the effect of M1 and M2 monocyte-derived macrophages on KFs in vitro. We focused on the effects of the macrophage secretome on fibrosis-related criteria in KFs, including proliferation, migration, differentiation, and ECM synthesis. First, we demonstrated that M2-like macrophages enhanced the fibrogenic profile of KFs in culture. Then, we surprisingly founded that M1-like macrophages can have an anti-fibrogenic effect on KFs, even in a pro-fibrotic environment. These results demonstrate, for the first time, that M1 and M2 macrophage subsets differentially impact the fibrotic fate of KFs in vitro, and suggest that restoring the M1/M2 balance to favor M1 in keloids could be an efficient therapeutic lever to prevent or treat keloid fibrosis.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

TEM1/endosialin/CD248 promotes pathologic scarring and TGF-β activity through its receptor stability in dermal fibroblasts

BACKGROUND

Pathologic scars, including keloids and hypertrophic scars, represent a common form of exaggerated cutaneous scarring that is difficult to prevent or treat effectively. Additionally, the pathobiology of pathologic scars remains poorly understood. We aim at investigating the impact of TEM1 (also known as endosialin or CD248), which is a glycosylated type I transmembrane protein, on development of pathologic scars.

METHODS

To investigate the expression of TEM1, we utilized immunofluorescence staining, Western blotting, and single-cell RNA-sequencing (scRNA-seq) techniques. We conducted in vitro cell culture experiments and an in vivo stretch-induced scar mouse model to study the involvement of TEM1 in TGF-β-mediated responses in pathologic scars.

RESULTS

The levels of the protein TEM1 are elevated in both hypertrophic scars and keloids in comparison to normal skin. A re-analysis of scRNA-seq datasets reveals that a major profibrotic subpopulation of keloid and hypertrophic scar fibroblasts greatly expresses TEM1, with expression increasing during fibroblast activation. TEM1 promotes activation, proliferation, and ECM production in human dermal fibroblasts by enhancing TGF-β1 signaling through binding with and stabilizing TGF-β receptors. Global deletion of Tem1 markedly reduces the amount of ECM synthesis and inflammation in a scar in a mouse model of stretch-induced pathologic scarring. The intralesional administration of ontuxizumab, a humanized IgG monoclonal antibody targeting TEM1, significantly decreased both the size and collagen density of keloids.

CONCLUSIONS

Our data indicate that TEM1 plays a role in pathologic scarring, with its synergistic effect on the TGF-β signaling contributing to dermal fibroblast activation. Targeting TEM1 may represent a novel therapeutic approach in reducing the morbidity of pathologic scars.

Activin A and Follistatin Serum Concentrations in Breast Augmentation Patients

Background: Capsular contracture is caused by an excessive fibrotic reaction similar as observed in other progressive fibrotic disorders. For their pathogenesis, several studies confirmed the importance of activins and follistatin. The aim of this study was to determine and analyze serum levels of Activin A and follistatin in patients with capsular contracture after aesthetic breast augmentation. Methods: The study included 361 female patients who underwent primary aesthetic breast augmentation, came for control examination after breast augmentation or for revision operation because of capsular contracture. Blood samples were taken and using a specific ELISA to determine the serum concentration levels of Activin A and Follistatin. Results: Ninety-six patients (n = 96), who developed a capsular contracture Baker ≥°III and underwent revision surgery were collected (capsular fibrosis group). One-hundred and fourteen patients (n = 114) were asymptomatic for capsular fibrosis Baker ≥°III after primary breast augmentation and 33 (n = 33) of them had developed no capsular fibrosis after more than 10 years (long-term group). For control group, blood samples were taken from 167 patients (n = 167) before primary aesthetic breast augmentation. Serum Activin A levels were significantly higher in the long-term Group compared with those in the capsular fibrosis- and the control groups. Follistatin levels were significantly lower in the capsular fibrosis group compared to the control- and the long-term groups. A small amount of control group patients (n = 16) developed a capsular fibrosis within 2 years after primary breast augmentation with significant lower follistatin levels. Retrospectively, they showed significantly lower serum follistatin levels than the control group even before the onset of capsular contracture. Conclusions: Capsular fibrosis has no effect on Activin A serum levels. In contrast, follistatin serum levels are lower in patients with capsular fibrosis. These results show that besides many other factors, a dysregulation of the Activin-follistatin axis may have importance on the pathogenesis of capsular contracture.

Salvianolic Acid B Attenuates Hypertrophic Scar Formation In Vivo and In Vitro

BACKGROUND

Hypertrophic scars (HTSs) are a fibroproliferative disorder that occur following skin injuries. Salvianolic acid B (Sal-B) is an extractant from Salvia miltiorrhiza that has been reported to ameliorate fibrosis in multiple organs. However, the antifibrotic effect on HTSs remains unclear. This study aimed to determine the antifibrotic effect of Sal-B in vitro and in vivo.

METHODS

In vitro, hypertrophic scar-derived fibroblasts (HSFs) were isolated from human HTSs and cultured. HSFs were treated with (0, 10, 50, 100 μmol/L) Sal-B. Cell proliferation and migration were evaluated by EdU, wound healing, and transwell assays. The protein and mRNA levels of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 were detected by Western blots and real-time PCR. In vivo, tension stretching devices were fixed on incisions for HTS formation. The induced scars were treated with 100 μL of Sal-B/PBS per day according to the concentration of the group and followed up for 7 or 14 days. The scar condition, collagen deposition, and α-SMA expression were analyzed by gross visual examination, H&E, Masson, picrosirius red staining, and immunofluorescence.

RESULTS

In vitro, Sal-B inhibited HSF proliferation, migration, and downregulated the expression of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 in HSFs. In vivo, 50 and 100 μmol/L Sal-B significantly reduced scar size in gross and cross-sectional observations, with decreased α-SMA expression and collagen deposition in the tension-induced HTS model.

CONCLUSIONS

Our study demonstrated that Sal-B inhibits HSFs proliferation, migration, fibrotic marker expression and attenuates HTS formation in a tension-induced HTS model in vivo.

NO LEVEL ASSIGNED

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An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

The Role of Interleukin 10 in Keloid Therapy: A Literature Review

INTRODUCTION

Keloids are pathological wound healing responses to dermal injuries. These scars may lead to considerable morbidity, but treatments remain challenging for physicians. Interleukin 10 (IL-10), a potent anti-inflammatory cytokine, plays a prominent role in fetal scarless regenerative healing; therefore, it may become a more targeted and effective therapy for keloids. This review aimed to obtain an overview of the background of keloid and IL-10 functions as its promising forthcoming treatment.

MATERIALS AND METHODS

Studies were sought from Pubmed, ScienceDirect, PLOS, and Clinical Key. Keywords are interleukin 10, keloid, and wound healing as Medical Subject Headings terms.

RESULTS AND DISCUSSION

Keloids and fetal scarless healing represent 2 opposing ends of the tissue repair spectrum. Promising multiple animal models have demonstrated successful regenerative healing promotion through IL-10 overexpression by its ability to minimize inflammatory wound microenvironment, downregulate transforming growth factor β/SMAD signaling pathway, increase extracellular matrix breakdown, and regulate extracellular matrix. These results have led to the development of clinical trials investigating human recombinant IL-10.

CONCLUSIONS

Interleukin 10 has the potential to become a more targeted and promising therapy of keloids owing to its pleiotropic effects.

Emerging insights into the immunological aspects of keloids

A special kind of scar, keloid, sometimes grows huge, disturbing patients in different ways. We discussed the pathogenesis of keloids and found researches about fibroblasts and collagen disorders, with little emphasis on immunity. Coupled with few effective treatments in keloid at present, we have focused on the immunological mechanisms of keloids with an aim to unravel some new therapeutic approaches in the future. In this review, the immunological processes are separately illustrated by the classification of different immune cells. In addition, we also discuss possible reasons for the repeated recurrence of keloids, the phenomenon of cell talks, and inflammation-related signal pathways involved in the pathogenesis of keloids.

Tgf-β superfamily and limb regeneration: Tgf-β to start and Bmp to end

Axolotls represent a popular model to study how nature solved the problem of regenerating lost appendages in tetrapods. Our work over many years focused on trying to understand how these animals can achieve such a feat and not end up with a scarred up stump. The Tgf-β superfamily represents an interesting family to target since they are involved in wound healing in adults and pattern formation during development. This family is large and comprises Tgf-β, Bmps, activins and GDFs. In this review, we present work from us and others on Tgf-β & Bmps and highlight interesting observations between these two sub-families. Tgf-β is important for the preparation phase of regeneration and Bmps for the redevelopment phase and they do not overlap with one another. We present novel data showing that the Tgf-β non-canonical pathway is also not active during redevelopment. Finally, we propose a molecular model to explain how Tgf-β and Bmps maintain distinct windows of expression during regeneration in axolotls.

Inhibitory Effect of the LY2109761 on the Development of Human Keloid Fibroblasts

Keloids are scars characterized by abnormal proliferation of fibroblasts and overproduction of extracellular matrix components including collagen. We previously showed that LY2109761, a transforming growth factor- (TGF-) β receptor inhibitor, suppressed the secretion of matrix components and slowed the proliferation of fibroblasts derived from human hypertrophic scar tissue. However, the exact mechanism underlying this effect remains unclear. Here, we replicated the above results in keloid-derived fibroblasts and show that LY2109761 promoted apoptosis, decreased the phosphorylation of Smad2 and Smad3, and suppressed TGF-β1. These results suggest that the development and pathogenesis of keloids are positively regulated by the Smad2/3 signaling pathway and the upregulation of TGF-β1 receptors. LY2109761 and other inhibitors of these processes may therefore serve as therapeutic targets to limit excessive scarring after injury.

Downregulation of CR6-interacting factor 1 suppresses keloid fibroblast growth via the TGF-β/Smad signaling pathway

Keloids are a type of aberrant skin scarring characterized by excessive accumulation of collagen and extracellular matrix (ECM), arising from uncontrolled wound healing responses. While typically non-pathogenic, keloids are occasionally regarded as a form of benign tumor. CR6-interacting factor 1 (CRIF1) is a well-known CR6/GADD45-interacting protein, that has both nuclear and mitochondrial functions, and also exerts regulatory effects on cell growth and apoptosis. In this study, cell proliferation, cell migration, collagen production and TGF-β signaling was compared between normal fibroblasts (NFs) and keloid fibroblasts (KFs). Subsequently, the effects of CRIF1 deficiency were investigated in both NFs and KFs. Cell proliferation, cell migration, collagen production and protein expressions of TGF-β, phosphorylation of Smad2 and Smad3 were all found to be higher in KFs compared to NFs. CRIF1 deficiency in NFs and KFs inhibited cell proliferation, migration, and collagen production. In addition, phosphorylation of Smad2 and Smad3, which are transcription factors of collagen, was decreased. In contrast, mRNA expression levels of Smad7 and SMURF2, two important inhibitory proteins of Smad2/3, were increased, suggesting that CRIF1 may regulate collagen production. CRIF1 deficiency decreases the proliferation and migration of KFs, thereby inhibiting their overgrowth via the transforming growth factor-β (TGF-β)/Smad pathway. CRIF1 may therefore represent a potential therapeutic target in keloid pathogenesis.

LncRNA COL1A2-AS1 promotes skin fibroblast apoptosis by repressing p-Smad3 and promoting β-catenin expression

LncRNA COL1A2-AS1 has been demonstrated to inhibit fibroblast proliferation of hypertrophic scars. However, the function of COL1A2-AS1 in normal skin fibroblasts remains poorly studied. Here, we report that overexpression of COL1A2-AS1 promoted normal skin fibroblast apoptosis. On the basis of mRNA-seq data and gene set enrichment analysis plus Kyoto encyclopedia of genes and genomes pathway analysis, 16 upregulated and 125 downregulated mRNAs were found; TGF-β, Wnt, and MAPK pathways were potentially involved. Western blot assay confirmed that overexpression of COL1A2-AS1 repressed p-Smad3 expression and promoted β-catenin expression. Furthermore, COL1A2-AS1 overexpression combined with either TGF-β1 or siRNA against β-catenin reversed the upregulation of apoptosis in the COL1A2-AS1 overexpression group. In conclusion, our study revealed the roles of COL1A2-AS1 in normal skin fibroblast apoptosis, with COL1A2-AS1 functioning by repressing p-Smad3 expression and promoting β-catenin expression.

Attenuation of Abnormal Scarring Using Spherical Nucleic Acids Targeting Transforming Growth Factor Beta 1

Abnormal scarring is a consequence of dysregulation in the wound healing process, with limited options for effective and noninvasive therapies. Given the ability of spherical nucleic acids (SNAs) to penetrate skin and regulate gene expression within, we investigated whether gold-core SNAs (AuSNAs) and liposome-core SNAs (LSNAs) bearing antisense oligonucleotides targeting transforming growth factor beta 1 (TGF-β1) can function as a topical therapy for scarring. Importantly, both SNA constructs appreciably downregulated TGF-β1 protein expression in primary hypertrophic and keloid scar fibroblasts in vitro. In vivo, topically applied AuSNAs and LSNAs downregulated TGF-β1 protein expression levels and improved scar histology as determined by the scar elevation index. These data underscore the potential of SNAs as a localized, self-manageable treatment for skin-related diseases and disorders that are driven by increased gene expression.

New Progress of Adipose-derived Stem Cells in the Therapy of Hypertrophic Scars

Burns are a global public health issue of great concern. The formation of scars after burns and physical dysfunction of patients remain major challenges in the treatment of scars. Regenerative medicine based on cell therapy has become a hot topic in this century. Adipose-derived stem cells (ADSCs) play an important role in cellular therapy and have become a promising source of regenerative medicine and wound repair transplantation. However, the anti-scarring mechanism of ADSCs is still unclear yet. With the widespread application of ADSCs in medical, we firmly believe that it will bring great benefits to patients with hypertrophic scars.

Smad‑binding decoy reduces extracellular matrix expression in human hypertrophic scar fibroblasts

The exact mechanisms underlying hypertrophic scarring is yet to be fully understood. However, excessive collagen deposition by fibroblasts has been demonstrated to result in hypertrophic scar formation, and collagen synthesis in dermal fibroblasts is regulated by the transforming growth factor-β1/Smad signaling pathway. In view of this, a Smad-binding decoy was designed and its effects on hypertrophic scar-derived human skin fibroblasts was evaluated. The results of the present study revealed that the Smad decoy attenuates the total amount of collagen, collagen I and Smad2/3 expression in scar fibroblasts. Data from RNA sequencing indicated that the Smad decoy induced more than 4-fold change in 178 genes, primarily associated with to the extracellular matrix, compared with the untreated control. In addition, results from quantitative real-time polymerase chain reaction further confirmed that the Smad decoy significantly attenuated the expression of extracellular matrix-related genes, including COL1A1, COL1A2 and COL3A1. Furthermore, the Smad decoy reduced transforming growth factor-β1-induced collagen deposition in scar fibroblasts. Data generated from the present study provide evidence supporting the use of the Smad decoy as a potential hypertrophic scar treatment.

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

Keloids constitute an abnormal fibroproliferative wound healing response in which raised scar tissue grows excessively and invasively beyond the original wound borders. This review provides a comprehensive overview of several important themes in keloid research: namely keloid histopathology, heterogeneity, pathogenesis, and model systems. Although keloidal collagen versus nodules and α-SMA-immunoreactivity have been considered pathognomonic for keloids versus hypertrophic scars, conflicting results have been reported which will be discussed together with other histopathological keloid characteristics. Importantly, histopathological keloid abnormalities are also present in the keloid epidermis. Heterogeneity between and within keloids exists which is often not considered when interpreting results and may explain discrepancies between studies. At least two distinct keloid phenotypes exist, the superficial-spreading/flat keloids and the bulging/raised keloids. Within keloids, the periphery is often seen as the actively growing margin compared to the more quiescent center, although the opposite has also been reported. Interestingly, the normal skin directly surrounding keloids also shows partial keloid characteristics. Keloids are most likely to occur after an inciting stimulus such as (minor and disproportionate) dermal injury or an inflammatory process (environmental factors) at a keloid-prone anatomical site (topological factors) in a genetically predisposed individual (patient-related factors). The specific cellular abnormalities these various patient, topological and environmental factors generate to ultimately result in keloid scar formation are discussed. Existing keloid models can largely be divided into in vivo and in vitro systems including a number of subdivisions: human/animal, explant/culture, homotypic/heterotypic culture, direct/indirect co-culture, and 3D/monolayer culture. As skin physiology, immunology and wound healing is markedly different in animals and since keloids are exclusive to humans, there is a need for relevant human in vitro models. Of these, the direct co-culture systems that generate full thickness keloid equivalents appear the most promising and will be key to further advance keloid research on its pathogenesis and thereby ultimately advance keloid treatment. Finally, the recent change in keloid nomenclature will be discussed, which has moved away from identifying keloids solely as abnormal scars with a purely cosmetic association toward understanding keloids for the fibroproliferative disorder that they are.

Topical delivery of 5-fluorouracil-loaded carboxymethyl chitosan nanoparticles using microneedles for keloid treatment

Keloids are induced by skin injuries such as surgeries, skin piercings, burns, and trauma. The intra-lesional injection of 5-fluorouracil (5-FU) is a promising therapy to treat keloid. However, local 5-FU injections have caused several side effects such as pain at administration and hyperpigmentation. This study suggests a safer and more effective 5-FU delivery system. We used microneedles to treat keloid because this method has the feasibility of self-administration without pain. In this study, 5-FU-loaded carboxymethyl chitosan (CMC) nanoparticles were prepared and characterized by various analytical methods and then coated on stainless solid microneedles. The blank CMC nanoparticles caused an increase in cell viability on human normal fibroblasts to 150%. In particular, the 5-FU-loaded CMC nanoparticles showed a significant inhibitory effect on the human keloid fibroblast to 16%. The intercellular uptake of the 5-FU-loaded CMC nanoparticles was observed on both human normal and keloid fibroblasts by using a confocal microscope. In addition, it was found that the nanoparticles showed an inhibition of TGF-β1 by ELISA. For topical drug delivery, it was confirmed that the nanoparticles coated onto the microneedles were dissolved and diffused at the administration site in the porcine dorsal skin model. According to these results, the suggested microneedle-mediated drug delivery system not only inhibits the human keloid fibroblasts by delivering drugs effectively into the keloids but also has the feasibility to self-administer without pain. Therefore, this new system including 5-FU-loaded CMC nanoparticles and microneedles has the potential to treat keloid scars. Graphical abstract.

Bone marrow mesenchymal stem cells improve spinal function of spinal cord injury in rats via TGF-β/Smads signaling pathway

Bone marrow mesenchymal stem cells (BMSCs) on the repair of spinal cord injury (SCI) in rats as well as the role of transforming growth factor-β (TGF-β)/Smads signaling pathway in the repair were investigated. Rat BMSCs and astrocyte-spinal cords (ASCs) were isolated and cultured in vitro, and the cell purity was detected by flow cytometry. ASCs were co-cultured with TGF-β1, BMSCs and BMSCs + TGF-β1, respectively, and grouped accordingly, and ASCs cultured conventionally were included into control group. 3-(4,5)-Dimethylthiahiazo(-z-y1)-3,5-diphenyltetrazoliumbromide (MTT) assay was conducted to detect the proliferation ability of ASCs in each group. Western blotting (WB) was utilized to examine the expression of TGF-β/Smads signaling pathway-related proteins [TGF-β1, Smad2 and phosphorylated (p)-Smad2] in ASCs and ASCs co-cultured with BMSCs. A rat model of SCI was established, and BMSCs were injected locally. Then (BBB) score was used to evaluate spinal cord repair, and WB was adopted to detect the expression of TGF-β1, Smad2 and p-Smad2 at the injured site. BMSCs and ASCs isolated in vitro grew well. According to MTT assay results, TGF-β1 significantly promoted the proliferation of ASCs (P<0.05), and co-culture of ASCs and BMSCs remarkably reduced the proliferation of ASCs (P<0.05). The detection of protein expression at the SCI site via WB demonstrated that the expression of TGF-β1, Smad2 and p-Smad2 in SCI group were obviously upregulated compared with those in Sham group at 1 week (P<0.05), and the injection of BMSCs could markedly downregulate the expression (P<0.05). After 3 week, there were no significant differences in the expression of TGF-β1, Smad2 and p-Smad2 among groups (P>0.05). The transplantation of BMSCs can improve the spinal function of SCI rats probably by inhibiting the TGF-β/Smads signaling pathway and reducing the proliferation of ASCs.

Tanshinone IIA attenuates silica-induced pulmonary fibrosis via inhibition of TGF-β1-Smad signaling pathway

Transforming growth factor-β 1 (TGF-β1) is a key mediator in fibrogenesis, and is upregulated and activated in fibrotic diseases. The exact role of TGF-β1-Smad signaling in the progression of silicosis fibrosis is yet to be conclusively determined. Using a Wistar rat silicosis model, we examined whether tanshinone IIA (Tan IIA) could meliorate silicosis fibrosis. The pulmonary fibroblasts of rats from the normal control group and silicosis-induced model group were extracted and examined so as to further explore the disruption of TGF-β1-Smad signaling pathway in silicosis pathogenesis and the intervention of Tan IIA in this pathway. Using RT-PCR, immunohistochemical staining, and immunofluorescence analysis, we determined that Tan IIA could ameliorate silicosis fibrosis, downregulate collagen I, collagen III, and α-SMA expression both, in vivo and in vitro. In silicosis fibroblasts, TGF-β1 induced phosphorylation of Smad2, Smad3, and negative feedback Smad7 inhibition in a dose dependent manner, and the phosphorylation of Smad3 persisted when the upstream signal was blocked. Tan IIA treatment effectively inhibited the TGF-β1-induced phosphorylation of Smads, especially the persistent phosphorylation of Smad3 in the nucleus, and upregulated the expression of Smad7 in silicosis fibroblasts, leading to a reduction in ECM deposition. Our findings indicate that dysregulation of the TGF-β1-Smad signaling pathway may play an important role in the pathological process of silicosis. Tan IIA thus ameliorates silicosis fibrosis partially by suppressing activation of TGF-β1-Smad signaling pathway, which may turn out to be a potential therapeutic approach to prevent silicosis fibrosis.

Role of Elevated Thrombospondin-1 in Kainic Acid-Induced Status Epilepticus

Previous studies have suggested that thrombospondin-1 (TSP-1) regulates the transforming growth factor beta 1 (TGF-β1)/phosphorylated Smad2/3 (pSmad2/3) pathway. Moreover, TSP-1 is closely associated with epilepsy. However, the role of the TSP-1-regulated TGF-β1/pSmad2/3 pathway in seizures remains unclear. In this study, changes in this pathway were assessed following kainic acid (KA)-induced status epilepticus (SE) in rats. The results showed that increases in the TSP-1/TGF-β1/pSmad2/3 levels spatially and temporally matched the increases in glial fibrillary acidic protein (GFAP)/chondroitin sulfate (CS56) levels following KA administration. Inhibition of TSP-1 expression by small interfering RNA or inhibition of TGF-β1 activation with a Leu-Ser-Lys-Leu peptide significantly reduced the severity of KA-induced acute seizures. These anti-seizure effects were accompanied by decreased GFAP/CS56 expression and Smad2/3 phosphorylation. Moreover, inhibiting Smad2/3 phosphorylation with ponatinib or SIS3 also significantly reduced seizure severity, alongside reducing GFAP/CS56 immunoreactivity. These results suggest that the TSP-1-regulated TGF-β1/pSmad2/3 pathway plays a key role in KA-induced SE and astrogliosis, and that inhibiting this pathway may be a potential anti-seizure strategy.

Understanding Keloid Pathobiology From a Quasi-Neoplastic Perspective: Less of a Scar and More of a Chronic Inflammatory Disease With Cancer-Like Tendencies

Keloids are considered as benign fibroproliferative skin tumors growing beyond the site of the original dermal injury. Although traditionally viewed as a form of skin scarring, keloids display many cancer-like characteristics such as progressive uncontrolled growth, lack of spontaneous regression and extremely high rates of recurrence. Phenotypically, keloids are consistent with non-malignant dermal tumors that are due to the excessive overproduction of collagen which never metastasize. Within the remit of keloid pathobiology, there is increasing evidence for the various interplay of neoplastic-promoting and suppressing factors, which may explain its aggressive clinical behavior. Amongst the most compelling parallels between keloids and cancer are their shared cellular bioenergetics, epigenetic methylation profiles and epithelial-to-mesenchymal transition amongst other disease biological (genotypic and phenotypic) behaviors. This review explores the quasi-neoplastic or cancer-like properties of keloids and highlights areas for future study.

Inhibition of USP4 attenuates pathological scarring by downregulation of the TGF‑β/Smad signaling pathway

Pathological scarring is a result of the hypertrophy of scar tissue during tissue repair following trauma. The aim of the present study was to assess the effect of ubiquitin‑specific protease 4 (USP4) silencing on pathological scarring, and to evaluate the mechanistic basis for the effect. An MTT assay was used to assess cell viability. Immunoprecipitation (IP) was used to determine ubiquitination levels of the TGF‑β receptor (TβR)I and Smad7. Tumor formation was assessed by injecting keloid fibroblasts. Hematoxylin and eosin staining was used to detect pathological changes in tumor tissue. Reverse transcription quantitative polymerase chain reaction and western blot analysis assays were used to evaluate the expression levels of TβRI and Smad7. Compared with the untreated control animals, cell viability and the expression of TβRI and Smad7 increased significantly in animals treated with TGF‑β. Short hairpin RNA for USP4 (shUSP4) decreased the cell viability of negative control cells, TGF‑β‑induced cellular proliferation, and the expression of TβRI and Smad7. IP experiments indicated that the ubiquitination level of TβRI was decreased following USP4 silencing. There was no remarkable difference in the structure of scar tissue among the various animal groups at 14 days following treatment, while the necrotic area of the scar tissue in the shUSP4 and vialinin A (USP inhibitor)‑treated animals increased significantly at the 28th and 42nd day compared with the control animals. At days 14, 28 and 42, the expression levels of TβRI and Smad7 in the shUSP4 and vialinin A‑treated animals were significantly decreased compared with the control animals (P<0.05). In summary, interference with or inhibition of USP4 prevented the activity of the TGF‑β/Smad pathway signaling and inhibited the formation of pathological scars.

Carboxyethyl aminobutyric acid (CEGABA) lacks cytotoxicity and genotoxicity and stimulates cell proliferation and migration in vitro

Cosmeceuticals are cosmetics formulated using compounds with medical-like benefits. Though the antiaging effect of carboxyethyl aminobutyric acid (CEGABA) has been discussed, its action mechanism in cosmeceuticals remains unclear. This study assessed the in vitro efficacy and safety of CEGABA. NHI-3T3 mouse fibroblast cell line was treated with two CEGABA concentrations (50 and 500 μmol/L) for 24 h, 48 h, and 72 h. Cytotoxicity and genotoxicity were evaluated by colorimetry (MTT) and the alkaline version of the comet assay, respectively. Flow cytometry and the scratch-wound assay were used to assess cell-cycle phase distributions and cell migration rates. Compared with the untreated control, CEGABA increased cell growth 1.6 times after 72 h, independent of dose. The compound also decreased cell replication time by 4 h. These findings seem to be related with the approximately 1.5-times increase in phase S cells numbers. Importantly, in vitro wound healing improved roughly 20% after treatment with CEGABA for 24 h and persisted after 48 h, indicating culture recovery. The time-dependent proliferation and migration of fibroblasts induced by CEGABA besides the fact that the compound is neither genotoxic nor cytotoxic makes it an ideal candidate in the development of cosmeceuticals in antiaging therapy.

A novel mechanism of Smads/miR-675/TGFβR1 axis modulating the proliferation and remodeling of mouse cardiac fibroblasts

Cardiac fibroblasts (CFs) can over-proliferate during the progression of cardiac fibrosis, accompanied by a net accumulation of extracellular matrix proteins. Based on the profibrotic actions of transforming growth factor beta 1 (TGFβ1), investigating the mechanisms of TGFβ1 function in CFs may provide new directions to treatment for cardiac fibrosis. microRNAs (miRNAs) could control CFs proliferation or remodeling via binding to 3'-untranslated region of messenger RNA (mRNA) to negatively regulate gene expression. In the present study, we downloaded several microarray analyses results from GEO attempting to identify miRNAs and possible downstream targets that may be involved in TGF-β1 function in CFs and to detect the cellular and molecular functions of the identified miRNA-mRNA axis. Here, we identified miR-675 as a downregulated miRNA by TGFβ1 by bioinformatics analyses and experimental verification. Upon TGFβ1 stimulation, the protein levels of Α-SMAΑ-SMA, collagen I, and POSTN, and the secreted collagen in the cell culture supernatant significantly increased, whereas the miR-675 expression decreased. Smads mediate TGFβ1-induced suppression on miR-675 via binding miR-675 promoter region. miR-675 overexpression could inhibit, whereas miR-675 inhibition could enhance TGFβ1-induced mouse CFs (MCF) remodeling and proliferation. TGFβ receptor 1 (TGFβR1), a critical receptor in TGFβ1/Smad signaling, is a direct downstream target of miR-675. TGFβR1 overexpression significantly reverses the effect of miR-675 overexpression on MCF remodeling and proliferation. In summary, miR-675 targets TGFβR1 to attenuate TGFβ1-induced MCF remodeling and proliferation. We demonstrate a novel mechanism of the Smads/miR-675/TGFβR1 axis modulating TGFβ1-induced MCF remodeling and proliferation.

KGF-1 accelerates wound contraction through the TGF-β1/Smad signaling pathway in a double-paracrine manner

KGF-1 plays an important role in the wound healing process. Loss of the KGF-1 gene in diabetic mice attenuated the process of wound contraction, suggesting that KGF-1 contributes to wound contraction. However, the mechanism remains unclear. To investigate the role of KGF-1 in diabetic wound contraction, we established a keratinocyte-fibroblast co-culture system. Concentrations of transforming growth factor β1 (TGF-β1) in conditioned supernatant treated with KGF-1 (KGF-1 group), tk;4KGF-1-neutralizing antibody (anti-KGF-1 group), TGF-β1 (TGF-β1tk;1 group), KGF-1 and TGF-β1-neutralizing antibody (KGF-1 + anti-TGF-β1 group) were tested by ELISA. Conditioned medium was added to fibroblast-populated collagen lattice (FPCL) to investigate the effect of KGF-1 on fibroblastqj contraction. TGF-β1, Col-I, p-Smad2, p-Smad3, and α-smooth muscle actin (α-SMA) were examined by Western blotting. A diabetic rat wound model was utilized to evaluate wound morphology, histology, immunohistochemistry, and protein expression in wound tissue after treatment with KGF-1. ELISA assays revealed that the concentration of TGF-β1 in the conditioned supernatant in the KGF-1 group was significantly higher. The contractile capacity of FPCL stimulated by conditioned medium derived from the KGF-1 group was significantly elevated; however, the contractile activity of FPCL induced by KGF-1 was attenuated by TGF-β1-neutralizing antibody. The Western blot results suggest that KGF-1 is able to stimulate TGF-β1 activation with increased Col-I, p-Smad2, p-Smad3, and α-SMA expression. Diabetic wounds treated with KGF-1 had a higher degree of contraction with significantly higher expression of TGF-β1, Col-I, p-Smad2, p-Smad3, and α-SMA. Our findings demonstrate that KGF-1 promotes fibroblast contraction and accelerates wound contraction via the TGF-β1/Smad signaling pathway in a double-paracrine manner.

Oncostatin M exerts a protective effect against excessive scarring by counteracting the inductive effect of TGFβ1 on fibrosis markers

Wound healing is a complex physiological process that repairs a skin lesion and produces fibrous tissue. In some cases, this process can lead to hypertrophic scars (HS) or keloid scars (KS), for which the pathophysiology remains poorly understood. Previous studies have reported the presence of oncostatin M (OSM) during the wound healing process; however, the role of OSM in pathological scarring remains to be precisely elucidated. This study aims to analyse the presence and involvement of OSM in the pathological scarring process. It was conducted with 18 patients, including 9 patients with hypertrophic scarring and 9 patients with keloid scarring. Histological tissue analysis of HS and KS showed minor differences in the organization of the extracellular matrix, the inflammatory infiltrate and the keratinocyte phenotype. Transcriptomic analysis showed increased expression levels of fibronectin, collagen I, TGFβ1, β-defensin-2 and S100A7 in both pathological samples. OSM expression levels were greater in HS than in KS and control skin. In vitro, OSM inhibited TGFβ1-induced secretion of components of the extracellular matrix by normal and pathological fibroblasts. Overall, we suggest that OSM is involved in pathological wound healing processes by inhibiting the evolution of HS towards KS by controlling the fibrotic effect of TGFβ1.

LY2109761 reduces TGF-β1-induced collagen production and contraction in hypertrophic scar fibroblasts

Hypertrophic scars (HS) are fibro-hyperproliferative dermal lesions with effusive continuous accumulation of extracellular matrix components, particularly collagen. They usually occur after dermal injury in genetically susceptible individuals and cause both physical and psychological distress for the affected individuals. Transforming growth factor-β1 (TGF-β1) is known to mediate wound healing process by regulating cell differentiation, collagen production and extracellular matrix degradation. The sustained high expression of TGF-β1 is believed to result in the formation of hypertrophic scars. Inhibition of TGF-β1 signaling pathway may represent one of effective strategies for limiting excessive scarring. LY2109761, an orally active TβRI/II kinase dual inhibitor, has been previously reported that it had inhibitory effects on carcinomas and attenuates Radiation-induced pulmonary murine fibrosis. Our results revealed that LY2109761 reduced TGF-β1-induced collagen production and α-smooth muscle actin (α-SMA) expression, and attenuated TGF-β1-induced cell contraction in hypertrophic scar fibroblasts. The data from this study provide evidence supporting the potential use of LY2109761 as a novel treatment for hypertrophic scars.

Fibroproliferative genes are preferentially expressed in central centrifugal cicatricial alopecia

BACKGROUND

Central centrifugal cicatricial alopecia (CCCA) is a primary cicatricial alopecia that most commonly affects women of African descent. Like CCCA, fibroproliferative disorders (FPDs) such as keloids, atherosclerosis, and fibroids are characterized by low-grade inflammation and irritation, resulting in end-stage fibrosis.

OBJECTIVE

We sought to determine whether fibroproliferative genes were up-regulated in patients with CCCA.

METHODS

A total of 5 patients with biopsy-proven CCCA were recruited for this study. Two scalp biopsy specimens were obtained from each patient; 1 from CCCA-affected vertex scalp and 1 from the unaffected occipital scalp. Microarray analysis was performed to determine the differential gene expression patterns.

RESULTS

There was an upregulation of genes implicated in FPDs in patients with CCCA. Specifically, we noted increased expression of platelet derived growth factor gene (PDGF), collagen I gene (COL I), collagen III gene (COL III), matrix metallopeptidase 1 gene (MMP1), matrix metallopeptidase 2 gene (MMP2), matrix metallopeptidase 7 gene (MMP7), and matrix metallopeptidase 9 gene (MMP9) in affected scalp compared with in unaffected scalp. Significant overlap in the canonic pathways was noted between patients with CCCA and patients with both atherosclerosis and hepatic fibrosis (P < .001).

LIMITATIONS

Small sample size and the use of whole skin tissue for analysis.

CONCLUSION

We have identified the upregulation of critical genes implicated in FPDs in the gene expression profile of patients with CCCA. These findings may help identify future therapeutic targets for this otherwise difficult-to-treat condition.

Knockdown of elF3a inhibits TGF‑β1‑induced extracellular matrix protein expression in keloid fibroblasts

Keloid formation is characterized by hyperproliferation of secretory and responsive keloid fibroblasts (KFs) and overproduction of extracellular matrix (ECM). Eukaryotic translation initiation factor 3 subunit A (eIF3a) one of the core subunits of the translation initiation complex, eIF3, has previously been reported to possess an anti‑fibrogenic effect. However, the role of eIF3a in keloid formation has not yet been investigated. Therefore, the present study examined the effect of eIF3a on transforming growth factor‑β1 (TGF‑β1)‑mediated ECM expression in KFs. The expression levels of eIF3a in human keloid tissues was evaluated using reverse transcription‑quantitative polymerase chain reaction and western blotting. KFs were incubated with siRNA‑eIF3a or siRNA‑mock for 48 h. The cells were then treated with TGF‑β1 (10 ng/ml) for 72 h. Cell proliferation was evaluated using the CCK‑8 assay. The expression levels of α‑SMA, collagen type I, TGF‑β receptor I (RI), TGF‑β RII, phosphorylated (p)‑mothers against decapentaplegic homolog (Smad2), Smad2, p‑Smad3 and Smad3 were detected western blotting. The present study identified significant upregulation of eIF3a mRNA and protein and in human keloid tissues compared with in normal tissues. Knockdown of eIF3a inhibited KF proliferation induced by TGF‑β1. In addition, eIF3a silencing significantly suppressed the TGF‑β1‑induced expression of α‑smooth muscle actin, collagen I, TGF‑β RI and TGF‑β RII in KFs. Furthermore, eIF3a silencing inhibited the phosphorylation levels of Smad2 and Smad3 in TGF‑β1‑induced KFs. To the best of our knowledge, the current study is the first to demonstrate that siRNA‑eIF3a inhibits the expression ECM proteins via the TGF‑β1/Smad signaling pathway in KFs. Therefore, eIF3a may be a potential, novel target for treatment of keloids.

The role of TGFβ in wound healing pathologies

Wound healing is one of the most complex processes in multicellular organisms, involving numerous intra- and intercellular signalling pathways in various cell types. It involves extensive communication between the cellular constituents of diverse skin compartments and its extracellular matrix. Miscommunication during healing may have two distinct damaging consequences: the development of a chronic wound or the formation of a hypertrophic scar/keloid. Chronic wounds are defined as barrier defects that have not proceeded through orderly and timely reparation to regain structural and functional integrity. Several growth factors are involved in wound healing, of which transforming growth factor beta (TGFβ) is of particular importance for all phases of this procedure. It exerts pleiotropic effects on wound healing by regulating cell proliferation, differentiation, extracellular matrix production, and modulating the immune response. In this review we are presenting the role of TGFβ in physiological and pathological wound healing. We show that the context-dependent nature of the TGFβ signaling pathways on wound healing is the biggest challenge in order to gain a therapeutically applicable comprehensive knowledge of their specific involvement in chronic wounds.

Downregulation of β-catenin blocks fibrosis via Wnt2 signaling in human keloid fibroblasts

Keloid is a disorder of fibroproliferative diseases that occurs in wounds, characterized by an exaggerated response to injury. The key factor responsible for the disease process has not been identified. This study sought to elucidate the role of β-catenin in the regulation of keloid phenotypes and signaling. Expression of β-catenin in keloid and normal non-keloid samples was measured by real-time polymerase chain reaction. Knockdown of β-catenin was achieved by delivering small interfering RNA to target β-catenin. Cell proliferation, cell cycle progression, and apoptosis of keloid cells were measured by functional assays in vitro. The proteins related to keloid fibrosis were measured by Western blotting. β-catenin expression was significantly upregulated in keloid tissue samples compared with the normal non-keloid age-adjusted skin sample counterparts. Functionally, targeting β-catenin with lipofection-delivered small interfering RNA oligonucleotide inhibited the proliferation and cell cycle arrest in G0/G1 phase and increased apoptosis of fibroblast cells, accompanied by downregulation of Wnt2 and cyclin D1 as well as the phosphorylation level of glycogen synthase kinase 3 beta in the keloid fibrosis. Our study supports a crucial role of β-catenin in the regulation of fibroproliferation and extracellular matrix deposition. Targeting β-catenin using small interfering RNA oligonucleotide may be a promising approach for preventing excessive fibroproliferative development after wound healing and may lead to the development of novel strategies for restoring keloid diseases.

In Situ Cytokine Expression and Morphometric Evaluation of Total Collagen and Collagens Type I and Type III in Keloid Scars

Keloids are characterized by excessive collagen deposition and growth beyond the edges of the initial injury, and cytokines may be related to their formation. The objective of this study was to evaluate the collagen fibers, analyze in situ expression of cytokines in keloid lesions, and compare to the control group. Results showed that there was a predominance of women and nonwhite and direct black ancestry. Keloid showed a significant increase in total and type III collagen. Significantly, the expression of mRNA for TGF-β in keloid was increased, the expressions of IFN-γ, IFN-γR1, and IL-10 were lower, and IFN-γR1 and TNF-α had no statistical difference. Correlations between collagen type III and TGF-β mRNA expression were positive and significant, IFN-γ, IFN-γR1, and IL-10 were negative and significant, and TNF-α showed no statistical difference. We conclude that there was a significant increase of total collagen in keloid and predominance of collagen type III compared to the controls, showing keloid as an immature lesion. There is a significant increase in TGF-β mRNA in keloid lesions, and a significant decrease in IFN-γ and IL-10, suggesting that these cytokines are related to keloid lesions.

miR-29b promotes skin wound healing and reduces excessive scar formation by inhibition of the TGF-β1/Smad/CTGF signaling pathway

The hypertrophic scar is a medical difficulty of humans, which has caused great pain to patients. Here, we investigated the inhibitory effect of miR-29b on scar formation. The scalded model was established in mice and miR-29b mimics or a negative control was subcutaneously injected into the injury skin. Then various molecular biological experiments were performed to assess the effect of miR-29b on scar formation. According to our present study, first, the results demonstrated that miR-29b was down-regulated in thermal injury tissue and miR-29b treatment could promote wound healing, inhibit scar formation, and alleviate histopathological morphologic alteration in scald tissues. Additionally, miR-29b treatment suppressed collagen deposition and fibrotic gene expression in scar tissues. Finally, we found that miR-29b treatment inhibited the TGF-β1/Smad/CTGF signaling pathway. Taken together, our data suggest that miR-29b treatment has an inhibitory effect against scar formation via inhibition of the TGF-β1/Smad/CTGF signaling pathway and may provide a potential molecular basis for future treatments for hypertrophic scars.

Low-Level Light Therapy with 410 nm Light Emitting Diode Suppresses Collagen Synthesis in Human Keloid Fibroblasts: An In Vitro Study

Background

Keloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare.

Objective

We investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts.

Methods

Keloid fibroblasts were isolated from keloid-revision surgery samples and irradiated using 410-, 630-, 830-nm light emitting diode twice, with a 24-hour interval at 10 J/cm². After irradiation, cells were incubated for 24 and 48 hours and real-time quantitative reverse transcription polymerase chain reaction was performed. Western blot analysis was also performed in 48 hours after last irradiation. The genes and proteins of collagen type I, TGF-β1, Smad3, and Smad7 were analyzed.

Results

We observed no statistically significant change in the viability of keloid fibroblasts after irradiation. Collagen type I was the only gene whose expression significantly decreased after irradiation at 410 nm when compared to the non-irradiated control. Western blot analysis showed that LLLT at 410 nm lowered the protein levels of collagen type I compared to the control.

Conclusion

LLLT at 410 nm decreased the expression of collagen type I in keloid fibroblasts and might be effective in preventing keloid formation in their initial stage.

Wound healing in cutaneous leishmaniasis: A double edged sword of IL-10 and TGF-β

Immune responses have a crucial role during the wound healing process in cutaneous leishmaniasis (CL). However, there are several paradoxes in immunity against CL. On the one hand, regulatory cytokines interleukin (IL)-10 and transforming growth factor beta (TGF-β) increase susceptibility to CL through suppression of several proinflammatory cytokines that require for defense against CL. On the other hand, these cytokines play a pivotal role in the acceleration of wound healing process. This review discusses about the dual role of IL-10 and TGF-β during the wound healing process and immunity against CL to offer a new insight about wound healing in CL.

Sulforaphane suppresses cell growth and collagen expression of keloid fibroblasts

Keloids are fibroproliferative diseases characterized by the accumulation of an extracellular matrix including collagen. Various growth factors, or cytokines, and their receptors are overexpressed in keloids, and they are expected to be therapy targets. Sulforaphane, a dietary isothiocyanate, has recently shown anti-tumor, anti-inflammatory, and anti-fibrotic properties. In this study, we found that sulforaphane inhibited cell growth and reduced collagen at the mRNA and protein levels in keloid fibroblasts. Moreover, sulforaphane markedly suppressed the expression of IL-6 and α-SMA and inhibited Stat3 and Smad3 signaling pathways in keloid fibroblast KF112 cells. Sulforaphane induced G2/M cell-cycle arrest with the induction of p21 in KF112 cells. In addition, sulforaphane inhibited cell growth and suppressed the expression of collagen in keloid fibroblasts under a coculture with peripheral blood mononuclear cells. Furthermore, sulforaphane suppressed IL-6, Stat3, and Smad3 signaling in the coculture system. This study suggests that sulforaphane may be a novel keloid treatment.

Partial epithelial-mesenchymal transition in keloid scars: regulation of keloid keratinocyte gene expression by transforming growth factor-β1

Background

Keloids are an extreme form of abnormal scarring that result from a pathological fibroproliferative wound healing process. The molecular mechanisms driving keloid pathology remain incompletely understood, hindering development of targeted, effective therapies. Recent studies in our laboratory demonstrated that keloid keratinocytes exhibit adhesion abnormalities and display a transcriptional signature reminiscent of cells undergoing epithelial-mesenchymal transition (EMT), suggesting a role for EMT in keloid pathology. In the current study, we further define the EMT-like phenotype of keloid scars and investigate regulation of EMT-related genes in keloid.

Methods

Primary keratinocytes from keloid scar and normal skin were cultured in the presence or absence of transforming growth factor beta 1 (TGF-β1) +/− inhibitors of TGF-β1 and downstream signaling pathways. Gene expression was measured using quantitative polymerase chain reaction. Migration was analyzed using an in vitro wound healing assay. Proteins in keloid scar and normal skin sections were localized by immunohistochemistry. Statistical analyses utilized SigmaPlot (SyStat Software, San Jose, CA) or SAS^® (SAS Institute, Cary, NC).

Results

In keloid and normal keratinocytes, TGF-β1 regulated expression of EMT-related genes, including hyaluronan synthase 2, vimentin, cadherin-11, wingless-type MMTV integration site family, member 5A, frizzled 7, ADAM metallopeptidase domain 19, and interleukin-6. Inhibition of canonical TGF-β1 signaling in keloid keratinocytes significantly inhibited expression of these genes, and TGF-β1 stimulation of normal keratinocytes increased their expression. The inhibition of the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway or the p38 mitogen-activated protein kinase pathway attenuated TGF-β1-induced expression of subsets of these genes. Migration of keloid keratinocytes, previously shown to be increased compared with normal keratinocytes, was significantly reduced by inhibition of TGF-β1 or ERK1/2 signaling. Biomarkers of EMT, including reduced E-cadherin and increased active β-catenin, were observed in keloid epidermis in vivo. However, evidence of basement membrane breakdown in keloid scar was not observed.

Conclusions

The results suggest that keloid keratinocytes exist in an EMT-like metastable state, similar to activated keratinocytes in healing wounds. The EMT-like gene expression pattern of keloid keratinocytes is regulated by canonical and non-canonical TGF-β1 signaling pathways. Therefore, interventions targeting TGF-β1-regulated EMT-like gene expression in keloid keratinocytes may serve to suppress keloid scarring.

Electronic supplementary material

The online version of this article (doi:10.1186/s41038-016-0055-7) contains supplementary material, which is available to authorized users.

Inhibitory effect of TGF-β peptide antagonist on the fibrotic phenotype of human hypertrophic scar fibroblasts

CONTEXT

TGF-β plays a central role in hypertrophic scar (HS) formation and development.

OBJECTIVE

This study investigated the role of a TGF-β antagonist peptide in inhibiting fibrotic behavior of human HS-derived fibroblasts (HSFs).

MATERIALS AND METHODS

HSFs were seeded at a density of 3.1 × 10(4)/cm(2) and were subjected to treatment of peptide antagonist (30 μM) or TGF-β receptor inhibitor LY2109761 (10 μM) or without treatment followed by the analyses of quantitative PCR, Elisa, in vitro wounding and fibroblast-populated collagen lattice (FPCL) assays.

RESULTS

qPCR and Elisa analyses showed that the peptide could, respectively, reduce the gene (at 48 h) and protein (at 72 h) expression levels of collagen I (86 ± 4.8%; 56.6 ± 7.3%), collagen III (73 ± 10.7%; 43.7 ± 7.2%), fibronectin (90 ± 8.9%; 21.1 ± 2.8%), and TGF-β1 (85 ± 9.3%; 25.0 ± 9.4%) as opposed to the non-treated group (p < 0.05), as the LY2109761 group similarly did. Cell proliferation was also significantly inhibited at day 5 (CCK-8 assay) by both peptide and LY2109761 treatments compared with the non-treated group (p < 0.05). The peptide also significantly inhibited cell migration as opposed to blank control at 24 h (43 ± 6.7% versus 60 ± 2.1%, p < 0.05) and at 48 h (63.9 ± 3.1% versus 95 ± 4.1%, p < 0.05). Similar to LY2109761, the peptide antagonist significantly reduced HS FPCL contraction compared with the non-treated group with significant differences in surface area at 48 h (0.71 ± 0.06 cm(2) versus 0.51 ± 0.06 cm(2), p < 0.05) and at 72 h (0.65 ± 0.02 cm(2) versus 0.42 ± 0.01 cm(2), p < 0.05).

CONCLUSION

The TGF-β antagonist peptide may serve as an important drug for HS prevention and reduction given the obvious benefits of good biosafety, low cost, and easy manufacture and delivery.

Sorafenib exerts an anti-keloid activity by antagonizing TGF-β/Smad and MAPK/ERK signaling pathways

Abstract

Keloid disease is characterized by hyperproliferation of responsive fibroblasts with vigorously continuous synthesis of extracellular matrix (ECM) components. Although the process by which keloids develop is poorly understood, most theories of the etiology are referred to fibroblast dysfunction. A central event in dermal repair is the release of growth factors in response to skin injury, which leads to the dysregulation of several crucial pathways that initiate the activation of keloid fibroblasts (KFs) and promote ECM accumulation. Hence, strategies aimed at reducing the production of these cytokines and/or disrupting their intracellular signal transduction have potential clinical significance for curing keloid. As the first oral multikinase inhibitor, sorafenib blocks a number of intracellular signaling pathways which are also pivotal for keloid pathogenesis. Therefore, evaluation of the effects of sorafenib on keloid disease seems timely and pertinent. In this study, we reported the identification of sorafenib that antagonized TGF-β/Smad and MAPK/ERK signaling pathways in primary KFs. Impressively, treatment with sorafenib inhibited KF cell proliferation, migration, and invasion, and simultaneously reduced collagen production in KFs. Furthermore, we present ex vivo evidence that sorafenib induced the arrest of KF migration, the inhibition of angiogenesis, and the reduction of collagen accumulation. These preclinical observations suggest that sorafenib deserves systematic exploration as a candidate agent for the future treatment of keloids.

Key message

The intracellular TGF-β/Smad and MAPK/ERK signaling pathways is blocked by sorafenib.

Sorafenib inhibits the proliferation, migration, invasion, and ECM deposition in keloid fibroblasts.

Sorafenib reduces KF migration and concomitantly angiogenesis in keloid explants.

Sorafenib is a promising agent for the treatment of keloids and hypertrophic scars.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-016-1430-3) contains supplementary material, which is available to authorized users.

Signalling by Transforming Growth Factor Beta Isoforms in Wound Healing and Tissue Regeneration

Transforming growth factor beta (TGFβ) signalling is essential for wound healing, including both non-specific scar formation and tissue-specific regeneration. Specific TGFβ isoforms and downstream mediators of canonical and non-canonical signalling play different roles in each of these processes. Here we review the role of TGFβ signalling during tissue repair, with a particular focus on the prototypic isoforms TGFβ1, TGFβ2, and TGFβ3. We begin by introducing TGFβ signalling and then discuss the role of these growth factors and their key downstream signalling mediators in determining the balance between scar formation and tissue regeneration. Next we discuss examples of the pleiotropic roles of TGFβ ligands during cutaneous wound healing and blastema-mediated regeneration, and how inhibition of the canonical signalling pathway (using small molecule inhibitors) blocks regeneration. Finally, we review various TGFβ-targeting therapeutic strategies that hold promise for enhancing tissue repair.

Protective role for miR-9-5p in the fibrogenic transformation of human dermal fibroblasts

Background

Excessive accumulation of extracellular matrix (ECM) proteins is the hallmark of fibrotic diseases, including skin fibrosis. This response relies on the activation of dermal fibroblasts that evolve into a pro-fibrogenic phenotype. One of the major players in this process is the cytokine transforming growth factor-β (TGF-β). MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression affecting a wide range of pathophysiological events including fibrogenesis. MicroRNA-9-5p (miR-9-5p) has been shown to exert a protective role in lung and peritoneal fibrosis. This study aimed to evaluate the role of miR-9-5p in skin fibrosis.

Results

miR-9-5p is up-regulated in TGF-β1-treated human dermal fibroblasts (HDFs). In silico identification of miR-9-5p targets spotted the type II TGF-β receptor (TGFBR2) as a potential TGF-β signaling-related effector for this miRNA. Consistently, over-expression of miR-9-5p in HDFs down-regulated TGFBR2 at both the mRNA and protein levels and reduced the phosphorylation of Smad2 and the translocation of Smad2/3 to the nucleus. In keeping, over-expression of miR-9-5p significantly delayed TGF-β1-dependent transformation of dermal fibroblasts, decreasing the expression of ECM protein collagen, type I, alpha 1 (Col1α1), and fibronectin (FN), the amount of secreted collagen proteins, and the expression of the archetypal myofibroblast marker alpha-smooth muscle actin (α-SMA). By contrast, specific inhibition of miR-9-5p resulted in enhanced presence of fibrosis markers. The expression of miR-9-5p was also detected in the skin and plasma in the mouse model of bleomycin-induced dermal fibrosis. Using lentiviral constructs, we demonstrated that miR-9-5p over-expression was also capable of deterring fibrogenesis in this same model.

Conclusions

miR-9-5p significantly prevents fibrogenesis in skin fibrosis. This is mediated by an abrogation of TGF-β-mediated signaling through the down-regulation of TGFBR2 expression in HDFs. These results may pave the way for future diagnostic or therapeutic developments for skin fibrosis based on miR-9-5p.

Electronic supplementary material

The online version of this article (doi:10.1186/s13069-016-0044-2) contains supplementary material, which is available to authorized users.

Visible Red Light Emitting Diode Photobiomodulation for Skin Fibrosis: Key Molecular Pathways

Skin fibrosis, also known as skin scarring, is an important global health problem that affects an estimated 100 million persons per year worldwide. Current therapies are associated with significant side effects and even with combination therapy, progression, and recurrence is common. Our goal is to review the available published data available on light-emitting diode-generated (LED) red light phototherapy for treatment of skin fibrosis. A search of the published literature from 1 January 2000 to present on the effects of visible red light on skin fibrosis, and related pathways was performed in January 2016. A search of PubMed and EMBASE was completed using specific keywords and MeSH terms. "Fibrosis" OR "skin fibrosis" OR "collagen" was combined with ("light emitting diode," "LED," "laser," or "red light"). The articles that were original research studies investigating the use of visible red light to treat skin fibrosis or related pathways were selected for inclusion. Our systematic search returned a total of 1376 articles. Duplicate articles were removed resulting in 1189 unique articles, and 133 non-English articles were excluded. From these articles, we identified six articles related to LED effects on skin fibrosis and dermal fibroblasts. We augmented our discussion with additional in vitro data on related pathways. LED phototherapy is an emerging therapeutic modality for treatment of skin fibrosis. There is a growing body of evidence demonstrating that visible LED light, especially in the red spectrum, is capable of modulating key cellular characteristic associated with skin fibrosis. We anticipate that as the understanding of LED-RL's biochemical mechanisms and clinical effects continue to advance, additional therapeutic targets in related pathways may emerge. We believe that the use of LED-RL, in combination with existing and new therapies, has the potential to alter the current treatment paradigm of skin fibrosis. There is a current lack of clinical trials investigating the efficacy of LED-RL to treat skin fibrosis. Randomized clinical trials are needed to demonstrate visible red light's clinical efficacy on different types of skin fibrosis.